Science Class 7 Chapter 16 -Water: A Precious Resource – NCERT Exercise Solutions (Question-Answer)

Science Class 7 – Chapter 16 -Water: A Precious Resource- NCERT Exercise Solution (Question-Answer) is provided below. Total 09 Questions are in this NCERT Exercise, all are solved here.

Q1. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world. (T/F)

Answer: True

(b) Water shortage is a problem faced only by people living in rural areas. (T/F)

Answer: False

(c) Water from rivers is the only source for irrigation in the fields. (T/F)

Answer: False

(d) Rain is the ultimate source of water. (T/F)

Answer: True

Q2. Explain how groundwater is recharged?

Answer: Groundwater is the water stored under the ground in the cracks and spaces in soil, sand, and rock. It is the major source of drinking water in both urban and rural India. Its availability depends on the rainfall and recharging capability of the soil. Rainwater seeps through the topsoil and layers of rocks like limestone, sand and fills the empty spaces and cracks deep below the ground. The process of seeping of water into the ground is called infiltration. Thus, Infiltration recharges the groundwater.

Q3. There are ten tube-wells in a lane of fifty houses. What could be the long-term impact on the water table?

Answer: If there are ten tube-wells in a lane of fifty houses then people will use that water mindlessly even for their domestic purpose because it is more than enough. This can lead to the depletion of the water table in the long run.

Q4. You have been asked to maintain a garden. How will you minimize the use of water?

Answer: If I have been asked to maintain a garden, I will minimize the use of wastage of water by the following process:

(i) Using the drip irrigation method for watering the plants. In this method, watering is done by dripping water drop by drop in the root zone either from above the soil surface or buried below the surface which also minimizes the evaporation. This saves a lot of water.

(ii) Recycling of water: Wastewater reuse or water reclamation is the process of converting wastewater into water that can be reused for other purposes which may include irrigation of gardens and agricultural fields or replenishing surface water and groundwater (i.e., groundwater recharge). This recycled water is also called Reclaimed water.

(iii) Rainwater harvesting: It is the collection and storage of rain, rather than allowing it to simply waste or run off. Rainwater is collected from a roof-like structured surface and redirected to a tank, reservoir, container, or deep pit (well, shaft, or borehole), etc. Rainwater harvesting differs from stormwater harvesting as the runoff is collected from roofs, rather than roads, drains, creeks, or any other land surfaces. It can be used as watering gardens, livestock, irrigation, domestic use with proper treatment. The harvested water can also be committed to longer-term storage or groundwater recharge.

Q5. Explain the factors responsible for the depletion of water table.

Answer: Factors responsible for the depletion of water table:

(i) Increasing population: As a result of the increasing population, more and more houses, shops, roads, offices, etc. are using water to fulfill their needs. This, in turn, increases the usage of water and more amount of wastewater is being produced.

(ii) Industrialization: Most of the stages of manufacturing processes in industries require water. As the number of industries increases, the water required by them also increases which contributes to the depletion of the water table.

(iii) Deforestation: Trees prevent soil erosion and also helps in replenish groundwater levels when it rains. Due to deforestation, the number of plants decreases. Hence, the water holding capacity of soil decreases, and thus the groundwater of that area is not recharged.

(iv) Agricultural activities: Water for agriculture is mainly obtained from rivers, canals, rainwater, groundwater, etc. Agriculture is impossible without water. Therefore, groundwater is the main source of water for agricultural activities, and this causes further depletion of the water table.

(v) Non-effective means of water conservation: A very little has been done to conserve freshwater sources. As we know, we use water mindlessly and exploit them because we think we have a lot of water. But it is wrong. We should conserve water because fresh drinking water is not unlimited. We must use them in a conservative way because it is precious.

Q6. Fill in the blanks with the appropriate answers:

(a) People obtain groundwater through _________ and __________________ .

Answer: wells, hand pump

(b) Three forms of water are ___________,____________ and _______.

Answer: solid, liquid, gas

(c) The water bearing layer of the earth is _____________.

Answer: aquifer

(d) The process of water seepage into the ground is called __________________.

Answer: infiltration

Q7. Which of the following is not responsible for water shortage?

(i) Rapid growth of industries

(ii) Increasing population

(iii) Heavy rainfall

(iv) Mismanagement of water resources

Answer: (iii) Heavy rainfall

Q8. Choose the correct option. The total water

(i) in the lakes and rivers of the world remains constant.

(ii) in the lakes and rivers of the world remains constant.

(iii) in the lakes and rivers of the world remains constant.

(iv) in the lakes and rivers of the world remains constant.

Answer: (iv) of the world remains constant.

Q9. Make a sketch showing groundwater and water table. Label it.


CBSE Science Class 7 Chapter 16 -Water: A Precious Resource- NCERT Exercise Solution (Question-Answer) ended here.👍👍👍

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